The present invention relates to an electronic system and components thereof for remotely controlling a locomotive. The system has a tilt sensor designed to operate in low temperatures often encountered in northern regions.
Economic constraints have led railway companies to develop portable master controllers allowing a ground-based operator to remotely control a locomotive in a switching yard. The portable master controller has a transmitter communicating with a slave controller on the locomotive by way of a radio link. To enhance safety, the portable master controller carried by the operator is provided with a tilt-sensing device to monitor the spatial orientation of the portable master controller and determine occurrence of operator incapacitating events, such as the operator tripping and falling over objects and loss of conscience due to a medical condition, among others. When the tilt-sensing device reports that the portable master controller is outside the normal range of inclination, the portable master controller will automatically generate, without operator input, a command signal over the radio link to stop the locomotive.
Tilt-sensing devices used by prior art portable master controllers are in the form of mercury switches. Those have proven unreliable in cold temperature operations where the mercury bead in the switch can freeze and loose mobility. Attempts to overcome this drawback include adding thallium to the mercury to lower its freezing point. This solution, however, is objectionable because thallium is a toxic substance. Hence, for environmental reasons, thallium is very rarely used in the industrial community.
Against this background, the reader will appreciate that a clear need exists in the industry to develop a system and components thereof for remotely controlling a locomotive, featuring tilt-sensing devices that can reliably operate in very low temperatures and do not use mercury or thallium materials in their construction.
In one broad aspect, the invention provides a portable master controller for a locomotive remote control system. The portable master controller has a user interface for receiving commands to control a movement of the locomotive. The user interface is responsive to operator commands to generate control signals. The portable master controller includes a processing unit receiving the control signals from the user interface to generate digital command signals directing the movement of the locomotive. A transmission unit receives the digital command signals and generates a RF transmission conveying the digital command signals to the slave controller.
A solid-state tilt sensor in communication with the processing unit communicates inclination information to the processing unit about the portable master controller. The processing unit receives and processes the inclination information. If the inclination information indicates that the portable master controller is in an unsafe operational condition, the processing unit generates an emergency digital command signal to the transmission unit, without input from the operator, for directing the locomotive to acquire a secure condition.
By xe2x80x9csolid-statexe2x80x9d is meant a tilt sensor that does not uses a liquid to produce inclination information.
In a specific and non-limiting example of implementation, the solid-state tilt sensor includes a single axis accelerometer responsive to the acceleration of gravity. Optionally, the accelerometer is a multi-axis device responding to vertical acceleration and acceleration in at least another axis, as well. The ability to assess acceleration levels in axes other than the vertical axis permits detection of unsafe conditions that do not necessarily translate into an excessive inclination of the portable master controller.
The inclination information sent by the solid-state tilt sensor can be in any form as long as it allows the processing unit to detect an unsafe operational condition. The determination as to what is safe and what is unsafe can vary greatly according to the specific application. All the variants, however, include a common denominator, which is an assessment of the degree of inclination of the portable master controller. In addition to the assessment of the degree of inclination, other parameters may be taken into account, such as the time during which the portable master controller remains beyond a certain inclination angle, among others.
Once the occurrence of an unsafe operational condition has been detected, the processing unit generates an emergency command signal to direct the locomotive to acquire a secure condition. A xe2x80x9csecurexe2x80x9d condition is a condition in which the risk of accident from the locomotive is substantially reduced. An example of a secure condition is stopping the locomotive.
In a second broad aspect, the invention provides a remote control system for a locomotive including in combination the portable master controller defined broadly above and the slave controller for mounting on-board the locomotive.
In third broad aspect, the invention provides a portable master controller that uses an accelerometer to generate inclination information.
Under a fourth broad aspect, the invention provides a remote control system for a locomotive that has a portable master controller using an accelerometer to generate inclination information.